EU police and customs officials cooperate closely to prevent smuggling of drugs, firearms, nuclear materials, pornography and goods liable to excise duty. (See Customs: Customs information system, Judicial-criminal, Police)
Moving goods across a customs frontier in a clandestine manner, evading customs control. It may be goods on which duty and taxes have been avoided, or it may be goods which are not permitted to be imported or exported.
Smuggling, or trafficking, is illegal transport, in particular across a border. Taxes are avoided; or the goods themselves are illegal for unlicensed possession; or people are transported to a place where they are not allowed to be.